How is the microbial diagnosis of bacterial vertebral osteomyelitis performed? An 11-year retrospective study

Risk Factors Preventing Identification of the Microorganism Causing Vertebral Osteomyelitis

STUDY DESIGN

Retrospective study.

OBJECTIVE

To elucidate the factors influencing the identification of causative microorganisms in vertebral osteomyelitis (VO) and the effectiveness of different culture methods in increasing the identification rate.

METHODS

A total of 252 patients diagnosed with and treated for VO at a single hospital were enrolled. The results of various culture methods were reviewed along with the clinical data of the patients retrospectively.

RESULTS

Microbiological diagnosis was achieved in 210 out of 252 patients (83.3%). Diagnostic percentages of blood cultures, CT-guided drainage, fluoroscopic disc biopsy, and intraoperative specimens were 73.6%, 73.9%, 27.6%, and 50.8%, respectively. Staphylococcus aureus was the most common pathogen (85 cases, 40.5%). Higher White Blood Cell (WBC) count, lower serum albumin (ALB) level, epidural abscess, and absence of prior antibiotic exposure were significant predictors of positive culture results across all culture methods. Prior antibiotic exposure was the most significant predictor of negative outcomes (OR 0.24). Blood culture results correlated with body temperature, C-reactive protein (CRP), ALB, and prior antibiotic exposure. A shorter duration of antibiotic administration before culture was associated with an increased likelihood of positive blood culture results.

CONCLUSIONS

This study demonstrated that laboratory findings indicating a high inflammatory response (elevated WBC count, CRP level, and body temperature), lower ALB level, presence of epidural abscess, absence of prior antibiotic exposure, and shorter duration of antibiotics were significant predictors of positive culture results. Blood cultures should be conducted in the presence of high inflammation levels to improve microorganism identification rates.

Culture-Negative Native Vertebral Osteomyelitis: A Narrative Review of an Underdescribed Condition

The incidence of culture-negative NVO (CN-NVO) cases is increasing, presenting significant diagnostic and therapeutic challenges due to the inability to isolate causative organisms with conventional microbiological methods. Factors influencing the diagnosis of CN-NVO include prior antimicrobial therapy, low pathogen burden, fastidious or intracellular organisms, technical issues, and non-infectious mimickers. Diagnosis often relies on imaging modalities like magnetic resonance imaging (MRI) and computed tomography (CT)-guided biopsy, though these methods can sometimes fail to yield positive microbiological results. Advanced diagnostic tools, such as polymerase chain reaction (PCR), metagenomic next-generation sequencing (mNGS), and cell-free DNA analysis, may be necessary to identify the pathogen. The causative pathogen cannot be isolated in some patients, among which an empirical antimicrobial therapy should be initiated. This narrative review discusses the management, monitoring, surgical indications, and outcomes for patients with CN-NVO.

A retrospective review of gram-negative spinal infections in a single tertiary spinal centre over six years

Aims

Gram-negative infections are associated with comorbid patients, but outcomes are less well understood. This study reviewed diagnosis, management, and treatment for a cohort treated in a tertiary spinal centre.

Methods

A retrospective review was performed of all gram-negative spinal infections (n = 32; median age 71 years; interquartile range 60 to 78), excluding surgical site infections, at a single centre between 2015 to 2020 with two- to six-year follow-up. Information regarding organism identification, antibiotic regime, and treatment outcomes (including clinical, radiological, and biochemical) were collected from clinical notes.

Results

All patients had comorbidities and/or non-spinal procedures within the previous year. Most infections affected lumbar segments (20/32), with Escherichia coli the commonest organism (17/32). Causative organisms were identified by blood culture (23/32), biopsy/aspiration (7/32), or intraoperative samples (2/32). There were 56 different antibiotic regimes, with oral (PO) ciprofloxacin being the most prevalent (13/56; 17.6%). Multilevel, contiguous infections were common (8/32; 25%), usually resulting in bone destruction and collapse. Epidural collections were seen in 13/32 (40.6%). In total, five patients required surgery, three for neurological deterioration. Overall, 24 patients improved or recovered with a mean halving of CRP at 8.5 days (SD 6). At the time of review (two to six years post-diagnosis), 16 patients (50%) were deceased.

Conclusion

This is the largest published cohort of gram-negative spinal infections. In older patients with comorbidities and/or previous interventions in the last year, a high level of suspicion must be given to gram-negative infection with blood cultures and biopsy essential. Early organism identification permits targeted treatment and good initial clinical outcomes; however, mortality is 50% in this cohort at a mean of 4.2 years (2 to 6) after diagnosis.

Clinical features and outcome of vertebral osteomyelitis after spinal injection: is it worth the price?

PURPOSE

Spinal injections are increasingly used for back pain treatment. Vertebral osteomyelitis (VO) after spinal injection (SIVO) is rare, but patient characteristics and outcome have not been well characterized. The aim of this study was to assess patient characteristics of SIVO in comparison to patients with native vertebral osteomyelitis (NVO) and to determine predictors for 1-year survival.

METHODS

This is a single-center cohort study from a tertiary referral hospital. This is a retrospective analysis of Patients with VO who were prospectively enrolled into a spine registry from 2008 to 2019. Student's t-test, Kruskal-Wallis test or Chi-square test were applied for group comparisons. Survival analysis was performed using a log-rank test and a multivariable Cox regression model.

RESULTS

283 VO patients were enrolled in the study, of whom 44 (15.5%) had SIVO and 239 (84.5%) NVO. Patients with SIVO were significantly younger, had a lower Charlson comorbidity index and a shorter hospital stay compared to NVO. They also showed a higher rate of psoas abscesses and spinal empyema (38.6% [SIVO] vs. 20.9% [NVO]). Staphylococcus aureus (27%) and coagulase-negative staphylococci (CNS) (25%) were equally often detected in SIVO while S. aureus was more frequently than CNS in NVO (38.1% vs. 7.9%).Patients with SIVO (P = 0.04) had a higher 1-year survival rate (Fig. 1). After multivariate analysis, ASA score was associated with a lower 1-year survival in VO.

CONCLUSION

The results from this study emphasize unique clinical features of SIVO, which warrant that SIVO should be estimated as a separate entity of VO.

CT-Guided Needle Biopsy in Vertebral Osteomyelitis: Study of Factors That Could Influence in Culture Yield

OBJECTIVE

The aim of this study was to analyze which are the main factors that could influence the result of a CT guided biopsy in vertebral osteomyelitis (VO) patients.

METHODS

A single center retrospective observational study was performed including adult patients who had been diagnosed with VO and undergone CT guided needle biopsy from January 2010 to January 2020. Demographical features, concurrent diseases, laboratory findings, microbiological diagnosis, radiological data, medical complications, antibiotic exposure were compiled. Multivariate analysis was performed with a logistic regression comparing the patients depending on the culture result.

RESULTS

Seventy-seven patients were included in the study. Baseline characteristics were comparable between groups. Sample culture was positive in 43 cases (56%). Microorganism isolated were gram+(72%), gram-(14%), mycobacteria (7%) and fungi (7%). Delay in the procedure, antibiotic exposure and blood culture positivity were also similar among both groups. The biopsy results were not influenced by the CRP value, the presence of fever nor antibiotic exposure. The longer duration of back pain was associated to a lower probability of a positive culture.

CONCLUSIONS

In conclusion, our study displays an acceptable reliability of CT guided needle biopsy in VO patients, even in cases under antibiotic treatment. The presence of fever or CRP values did not predict a positive culture. Delay in diagnosis could impact negatively on culture yield.

Is There a Difference in Clinical Features, Microbiological Epidemiology and Effective Empiric Antimicrobial Therapy Comparing Healthcare-Associated and Community-Acquired Vertebral Osteomyelitis?

Background: Empiric antibiotic therapy for suspected vertebral osteomyelitis (VO) should be initiated immediately in severely ill patients, and might be necessary for culture-negative VO. The current study aimed to identify differences between community-acquired (CA) and healthcare-associated (HA) VO in terms of clinical presentation, causative pathogens, and antibiotic susceptibility. Methods: Cases of adult patients with VO treated at a German university orthopaedic trauma center between 2000 and 2020 were retrospectively reviewed. Patient history was used to distinguish between CA and HA VO. Susceptibility of antibiotic regimens was assessed based on antibiograms of the isolated pathogens. Results: A total of 155 patients (with a male to female ratio of 1.3; and a mean age of 66.1 ± 12.4 years) with VO were identified. In 74 (47.7%) patients, infections were deemed healthcare-associated. The most frequently identified pathogens were Staphylococcus aureus (HAVO: 51.2%; CAVO: 46.8%), and Coagulase-negative Staphylococci (CoNS, HAVO: 31.7%; CAVO: 21.3%). Antibiograms of 45 patients (HAVO: n = 22; CAVO: n = 23) were evaluated. Significantly more methicillin-resistant isolates, mainly CoNS, were found in the HAVO cohort (27.3%). The highest rate of resistance was found for cefazolin (HAVO: 45.5%; CAVO: 26.1%). Significantly higher rates of resistances were seen in the HAVO cohort for mono-therapies with meropenem (36.4%), piperacillin–tazobactam (31.8%), ceftriaxone (27.3%), and co-amoxiclav (31.8%). The broadest antimicrobial coverage was achieved with either a combination of piperacillin–tazobactam + vancomycin (CAVO: 100.0%; HAVO: 90.9%) or meropenem + vancomycin (CAVO: 100.0%; HAVO: 95.5%). Conclusion: Healthcare association is common in VO. The susceptibility pattern of underlying pathogens differs from CAVO. When choosing an empiric antibiotic, combination therapy must be considered.

Novel strategies to diagnose prosthetic or native bone and joint infections

INTRODUCTION

Bone and Joint Infections (BJI) are medically important, costly and occur in native and prosthetic joints. Arthroplasties will increase significantly in absolute numbers over time as well as the incidence of Prosthetic Joint Infections (PJI). Diagnosis of BJI and PJI is sub-optimal. The available diagnostic tests have variable effectiveness, are often below standard in sensitivity and/or specificity, and carry significant contamination risks during the collection of clinical samples. Improvement of diagnostics is urgently needed.

AREAS COVERED

We provide a narrative review on current and future diagnostic microbiology technologies. Pathogen identification, antibiotic resistance detection, and assessment of the epidemiology of infections via bacterial typing are considered useful for improved patient management. We confirm the continuing importance of culture methods and successful introduction of molecular, mass spectrometry-mediated and next-generation genome sequencing technologies. The diagnostic algorithms for BJI must be better defined, especially in the context of diversity of both disease phenotypes and clinical specimens rendered available.

EXPERT OPINION

Whether interventions in BJI or PJI are surgical or chemo-therapeutic (antibiotics and bacteriophages included), prior sensitive and specific pathogen detection remains a therapy-substantiating necessity. Innovative tests for earlier and more sensitive and specific detection of bacterial pathogens in BJI are urgently needed.

Case report of infective spondylodiscitis due to nalidixic acid-resistant Salmonella paratyphi A

Spondylodiscitis due to typhoidal Salmonella presents a therapeutic challenge for clinicians. Factors that complicate treatment include drug-resistant strains, poor antibiotic bone penetration, potential for neurological compromise and lack of established protocols and guidelines. We discuss a 57-year-old man with Salmonella paratyphi A spondylodiscitis involving lower thoracic vertebrae and discuss various aspects of management.

Sneathia amnii, an unusual pathogen in spondylitis: A case report

Sneathia amnii is an opportunistic pathogen of the female reproductive tract that has been reported to cause infections during pregnancy and in the post-partum period. Infections outside the reproductive tract have rarely been described. We report the case of a spondylitis due to S. amnii in a 72-year old woman, successfully treated after seven weeks of antimicrobial therapy. Growth of this pathogen guided our diagnosis towards a gynecological pathology; we discovered an endometrium adenocarcinoma. This case emphasizes the need for adequate incubation of discal biopsies, using aerobic and anaerobic enrichment broth with prolonged incubation.